William r



(No Model.)

W. R. PATTERSON.

ELECTRIC CABLE.

Patented June '7, 1892.

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(,6 Q4, We 1/ UNITED STATES PATENT OFFICE.

\VILLIAM R. PATTERSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE IVESTERNELECTRIC COMPANY, OF SAME PLACE.

ELECTRIC CABLE.

SPECIFICATION forming part of Letters Patent No. 476,484, dated June 7,1892. Application filed October 29, 1891. Serial No. 410,241. (Nomodel.)

T aZZ whom it may concern.-

Be it known that I, WILLIAM R. PATTER- SON, a citizen of the UnitedStates, residing at Chicago, in the county of Cook and State ofIllinois,have invented a certain new and useful Improvement in Cables,of which the following is a full, clear, concise, and exact description,reference being had to the accompanying drawing, forming a part of thisspecifi- Io cation.

My invention relates to cables in which a core consisting of insulatedconducting wire or wires is surrounded by a sheath of lead or similarmaterial; and its object is to secure a I5 cable of low electrostaticcapacity and at the same time one in which the sheath will not be liableto buckle when the cable is bent. It is well known that in order to makeat cable of the lowest electrostatic capacitya large part of theinsulating material. must be air and the core must fit loosely in thesheath. To accomplish this, a soft and yielding core is required, sothat when a large cable so made with a soft and yielding core is bent,

as it is necessary to do in coiling it around manholes and in othersimilar situations, the pipe buckles to such an extent that it isimpracticable to straighten it out without breaking the pipe. If, on theother hand, the core 0 is made hard and dense and the sheath fits thecore tightly, the cable can be bent more readily; but the electrostaticcapacity of the conductors is thereby increased and the electricalefficiency of the cable consequently diminished. To secure rigidityandatthesame time retain the soft core and the air-spaces, which are anessential feature of the lowcapaeity cable, I make the sheath withinterior projecting longitudinal ribs, preferably integral with thesheath. These ribsbear against the core, leaving the spaces between theribs filled with air.

A better understanding of my invention will be obtained by reference tothe accompanying drawing, in which the pipe a has 5 upon its interiorand running longitudinally with the pipe the ribs 1) b 7), preferablyintegral with the pipe and formed upon itsinner surface in the processof drawing the pipe. The air-spaces c c c are between outer serv- 5o ing(1 of the core 6 and the inclosing sheath or pipe, which is preferablyformed of lead, or an alloy of lead.

Having thus described my invention, what I claim as new, and desire tosecure by Let- 5 5 ters Patent, is

In an electric cable, the combination, with a core of insulatedconductor or conductors, of an exterior metallic sheath havinginteriorprojecting longitudinal ribs in contact with the core, substantially asdescribed.

In witness whereof I hereunto subscribe my name this 17th day ofOctober, A. D. 1891.

IVILLIAM R. PATTERSON.

Witnesses:

FRANK R. MCBEETY, GEORGE L. CRAGG.

